Updated October 2022 By Dante Moroni
Rumors of Corona Extra’s low gluten content can be heard often in the gluten free community. This may be due to it being one of a few barley beers with known competitive ELISA results (R5 Antibody) verifying the low gluten level. A 2009 Swedish study showed it having <10ppm gluten.1 There are also several other bloggers online that have tested it with lateral flow devices and the result has usually been negative.
Out of my own curiosity I have decided to run a test on Corona Extra using EZ Gluten as part of my ongoing gluten in beer research.
My initial read on the test strip was negative, <10ppm (January 2022). However, after more thought, the line is a bit faint and suspect… I ended up running another test in October 2022 and that time it was convincingly positive.
After seeing this, it seems that Corona may indeed have more than >10ppm gluten, but it may depend on the batch and brewing conditions etc, and/or the testing device used. On top of that, the polyclonal antibody used in EZ Gluten could potentially be picking up non-immunogenic wheat sub-fractions, like HMW-glutenin.